This application claims the priority benefit of Taiwan application serial no. 88105504, filed Apr. 7, 1999, the full disclosure of which is incorporated herein by reference.
1. Field of Invention
The present invention relates to a method for planarizing an oxide layer. More particularly, the present invention relates to a method for planarizing an oxide layer using an isotropic chemical dry etching operation.
2. Description of Related Art
Conventionally, an oxide layer is planarized by performing a chemical-mechanical polishing operation. However, to produce a planar oxide layer above a highly rugged semiconductor substrate, a very thick layer of oxide must be deposited. Then, a chemical-mechanical polishing operation has to be carried out to remove the upper portion of the oxide layer so that the underlying rugged landscape is completely concealed. Since a rather thick oxide layer must be removed to obtain the desired planarity, polishing time is long and hence the cost of production will increase. Moreover, additional problems related to reliability of devices may result from lengthy polishing.
The invention provides a method of planarizing an oxide layer. The method includes performing an isotropic chemical dry etching operation using a nitrogenous processing gas. Furthermore, oxygen can also be added to the nitrogenous processing gas during the isotropic chemical dry etching operation.
According to the embodiment of this invention, the nitrogenous gas can be nitrogen or a nitrogen-oxygen compound, where the nitrogen-oxygen compound can be nitrogen monoxide, nitrogen dioxide or nitrous oxide.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.